Plural pressure pump control for hydraulic presses



Aug.9, 1932. 'W RNS 1 1,870,501

PLURAL PRESSURE PUMP CONTROL FOR HYDRAULIC PRESSES Filed July 14, 1931 2Sheets-Sheet 1 3rwentor,

Wwlimsi, 47

Gttor11egS.

Aug. 9, 1932. l w. ERNST 1,870,501

I PLURAL PRESSURE PUMP CONTROL FOR HYDRAULIC PRESSES Filed July 14, 1931Z'Sheets-Sheet 2 Snnentor,

Gttornegs,

Patented Aug. 9, 1932 UNITED A-CSTATES PATENT. OFFICE WALTER EBNSTJOI MOUN'JI GILEAD, OHIO, ASSIGNOB TO THE HYDRAULIC PRESS MANUFACTURINGCOMPANY, OF MOUNT GILEAD, OHIO PLURAL PRESSURE PUMP CONTEON FOBHYDRAULIC P338818 Application fled m 14, 1931. Serial ll'o. 550,771.

This invention relates generally to hydraulic presses of the typewherein .is provided a travelling ram and a pump capable of having itsoutput varied and which supplies a the pressure fluid utilized forimparting travel to' the press ram, and the invention primarily has foran object to provide novel means for so controlling the output of thepump as to subject the ress ram, at any 10 given interval, to aselecteof selective, predetermined and fixed operating pressures. I

Another object of the invention is to provide means by the employment ofwhich it is 1.: possible to vary the pressure values of the selective,predetermined and fixed operating pressures. This inventive feature alsoprovides for adjustment of the pressure values without disturbing therelation which the 29 selective operating pressures bear one to another.

My present invention is adaptable to use in connection with varioustypes of variable output pumps and in this disclosure I have chosen toillustrate my improved control devices in combination with a form ofthis type of pump which-is well known in the art. Pumps of this type areexemplified by the pump disclosed in United States Letters Patent1,250,170, granted to Hele-Shaw et al., De-

cember 18, 1917. Briefly stated, such pumps include a plurality ofradially arranged cylinders and pistons, the rate of discharge effectedby which depends upon the eccentricity 35 of the cylinder and pistonassembly relatively to adrive shaft. The cylinders are usually carriedby a floating ring or the like, which, by means of a cross head or othercontrol element, may be shifted to vary the eccentricity '40 of thecylinders and thereby efi'ect control of the pump output..

. In its more detailed nature the invention resides in the provision ofmeans tending to hold the pump control element or cross head at themaximum output effecting position,

one of a plurality means responsive to operating pressure being appliedto the press ram and effective upon attainment of one or another of aplurality of selective, fixed and predetermined operating pressures toresist the holding tendency and cooperatewith the holding means inmaintaining the selected operating pressure, and means to select theoperating pressure desired to be maintained. Another object of theinvention is to provide means to vary the holding tendency of theholding means so as to vary the values of the selective operatingpressures without varying the relation which the individual operatingpressures bear one to another.

Other objects will in part be obvious and in part be pointed outhereinafter.

To the attainment of the aforesaid objects and ends, the invention stillfurther resides in the novel details of construction, combination andarrangement of parts, all of which will be first fully described in thefollowing detailed description, then be par- I ticularly pointed out inthe appended claim, reference being had to the accompanying 70 drawings,in which Figure I is a somewhat diagrammatic side elevation illustratinga hydraulic press embodying my invention, the press cylinder and thecontrol devices associated with the pump being shown in section.

Figure 2 is a plan view of the pump, the attached control devices beingshown in horizontal section.

Figures 3 and 4 are diagrammatic face views of the pressure face of thecontrol piston and respectively illustrate, by shaded areas, theareasefiective during low and high pressure operation; adjustments.

In the drawings, in which like reference characters indicate like partsin all of the figures, A generally designates the'hydraulic press whichin this particular disclosure is of the fluid pressure'propelled gravityreturn type; B generally designates the variable output pum by which thepressure fluid utilized in t e operation of the press is delivered; Cgenerally designates the pressure responsive plural pressure controlmechanism; D, the plural pressure control adjustment mechanism and E thefluid tank which forms a part of the closed hydraulic circuit whichincludes the operating pump.

The press A includes the usual frame 5, a pressure cylinder 6, and thetravelling ram 7 which is of the pressure projected gravity return typeas' above outlined.

The pump B includes the housing 8, and inlet and outlet ports designated9 and 10 respectively. The inlet port 9 is connected by a suction pipeline 11 with the tank E,

' and the outlet port 10 is connected by a pressure ipe 12 with thecylinder 6 beneath the ram A return line 13 provides communicationbetween the cflinder 6 and the tank E, and a cut-oil valve 4 is providedin the line 13 for a purpose that Wlll become apparent as thedescription progresses.

The pump B in this particular disclosure is of the Hele-Shaw typedisclosed in United States Letters Patent 1,250,170 hereinbeforereferred to, andincludes the usual shiftable control rods or elements15. The rods project in the usual manner at opposite sides of the pump,those pro'ecting at the right-hand side being connecte by a cross-head16 and those at the left-hand side being connected by a cross-head 17.As will be evident by reference to Fi re 2, the shiftable controlelements comprising the cross-heads 16 and 17 and the control rods areconnected to the pump rings so that when these devices are shifted tothe right they will serve to bring about'the maximum output of which thepump is capable and whenshifted to the left the output of the pump willbe accordingly diminished in a manner well understood in the art.

The control mechanism C includes the pressure 0 linder 15 which issecured as at 19 to the rig t-hand side of the pum housing and thepiston plunger 20 is opera la in the cylinder 18, being mounted upon areduced diameter stem 21 which projects through a suitable packing gland22 and is attached as at 23 to the cross-head 16. By reason of theprovision of the stem at one side onl of the piston plunger this plungeris provi ed with a large area pressure face at its right-hand side andwith a smaller area pressure face at its left-hand side. The purpose forthis multi-area ordifierential area pressure face provision will becomeapparent as the description progresses.

A three-way pressure selection valve 25 is provided, the casing of whichis equipped with a common port 26 which is connected by a duct 27 withthe left-hand end of the cylinder 18 for communication with the smallerarea pressure face of the piston plunger, and

the casing of this valve is also provided with selective ports 28 and29, the former of which is connected by a pipe line or duct 30 with thepressure pipe line 24, and the latter of which is connected by a duct orpipe line 31 with the tank E. The rotatable core of the valve isprovided with an elbow .duct 32, and, by rotation of this core, it ispossible to bring about communication between the common port 26 and aselected one of the selective ports 28 and 29 in a well-known manner.

Thus it will be seen that, when the valve is positioned as illustratedin Figure 1, it will serve to open communication between the lefthandend of the cylinder 18 and the tank E through the pipe line or duct 27,the port 26, the duct 32, the port 29, and the duct or pipe line 31. Inthis adjustment of the valve, and at all times, the right-hand end ofthe cylinder 18 is in communication with the pressure pipe line 12through the pipe line or duct 24. When the valve core is turned so thatthe duct 32 connects the ports 26 and 28, both sides or pressure facesof the piston plunger 20 will be subjected to the pressure in the pipeline 12, in one instance directly through the pipe line connection 24and in the other instance through a portion of the pipe line 24, theduct 30, port 28, duct 32, port 26 and pi line or duct 27 he pressurecontrol adjustment mechanism D includes a bracket 33 which is secured asat 34 to the left-hand side of the pump housing and a rod 35, which issecured at one end as at 36 to the bracket 33, has its free endprojected from the bracket and threaded as at- 37 to receive theadjuster hand-wheel 38. The cross-head 17 is apertured as at 39 toreceive the rod and permit movement of the cross-head relatively to thisstationary rod.

An open-ended casing flange 40 projects from the bracket 33 and acup-like casing end or cap 41 is telescopically mounted on the extendedend thereof and forms an end abutment for the compression spring 42which is coiled about the rod 35 between the end cap 41 and thecross-head 17.

An anti-friction thrust bearing 43 equipment is interposed between thehand wheel 38 and the end cap 41 so that the hand wheel may be rotatedwithout imparting rotation to the end cap. By rotating the hand wheel 38in one direction or another on the threaded end of the rod 35, it ispossible to suitably increase or diminish the compression of the spring42 and thus increase or diminish the tendency of this spring to forcethe shiftable pump output controlling devices 17, 16, 15 toward themaximum output effecting position.

In operation the compression of the spring 42 isadjusted to impose apredetermined load on the cross-head 17 tending to shift this cross-headand the remaining output control elements 16, 15 toward the right andthereby bring about a maximum'output condition of the pump. Ashereinbefore stated the spring 42 constantly tends to force the controldevices to or hold the control devices at a position for. bringing abouta maximum output of the pump, and this forcing or holding terfilency ofthe spring 42 may be adjusted at m In the operation of the press it isdesired to maintain a constant predetermined operating pressure.At'times it is desirable to operate the press at a predetermined highpressure and at other times at a predetermined low pressure. In thisdisclosure, I have illustrated means for maintaining the desired high orlow operating pressure determined by the particular setting of thepressure selection valve 25.

When the valve 25 is in one position and a high pressure value is causedto act in opposition to the spring 42 which overcomes the tendency ofthat spring to move the pump control devices to the maximum dischargeeifecting position when a relatively lowopcrating pressure has beenbuilt up in the press cylinder 6, and when the valve is shifted to itsother position, a relatively low pressure value will be presented inopposition to the spring 42 so that the effect of this spring will beovercome only after attainment of a relatively high operating pressurein the,

press cylinder 6.

Thus, it is possible to operate the press at.

one or another of a plurality of selective, fixed, and predeterminedoperating pressures, which may be selected by manipulation of the valve25. It should also be understood that, by adjusting the compression ofthe spring 42, it ispossible to vary the selective operating pressurevalues without disturbing or varying the relation which the selectiveoperating pressures bear one to another With parts'adjusted asillustrated in Figure 1, the fluid discharged by the pump through thepressure line 12 will enter the cylinder 6 and force the ram 7 upwardly.The spring 42 will force the pump output control devices toward themaximum outputposition until the predetermined 10w operating pressuredesired has been attained in the cylinder 6- and pipe line 12, when thispressure will act through the pipe line 'or duct 24 against the largearea pressure face of the piston plunger 20. resistlng the efl'ort ofthe spring 42 and, if necessary, forcing the control devices 16, 15, 17toward the left in order to reduce the output of the pump and thusmaintain operation of the press at the desired operating pressure. Withthe parts thus set for press operation at low pressure, the whole areaat the right-hand face of the piston plunger 20 is efl'ective inresisting the function of the spring 42 (see shade lines in Figure 3) inview of the fact that the opposite end of the cylinder 18 is opened tofree communication with the tank E through connections 27, 26, 32, 29,and 31.

When the valve is shifted so that the duct 32 connects the ports 26 and28 the control devices are set for press operation at a fixed andpredetermined high pressure. In this setting of the valve, both faces ofthe piston plunger 20 are subjected to the pressure in the presscylinder and pipe line 12 with the net result that the small ,areaindicated by shade lines in Figure 4 alone reacts against the action ofthe spring and cooperates therewith in holdin the pump output at theselected fixed an predetermined high operating pressure.

As previously described, the press disclosed herein is of the typewherein the platen is pressure-projected and gravityreturned- During theworking stroke of thepress ram the valve 14 is, of course, closed, andon the return stroke, as the ram is descendingby gravity, this valve isopened to permit the pressure fluid to return to the tank E through thereturn line 13.

From the foregoing description, taken in connection with theaccompanying drawings, it is thought the novel details of construction,the manner of use, and the advantages of myinvention will be readilyapparent to those skilled in the art to which it relates.

I claim:

A control mechanism to actuate a ram or the like, in combination with avariable output pump having a housing, control means therein providedwith shiftable control rods at diametrically opposite sides slidablethrough and projecting beyond'the housing, spring mechanism exteriorlyof the pump having a cross head connected to the control rod at one sideof the housing, a plural pressure control mechanism including a cylindermember, a pair of spaced, apart supporting members extending from thecylinder member and attached to the said housing and offsetting thecylinder member therefrom, a piston operable in the cylinder memberhaving a stem extending through the end of the cylinder member facingthe pump and provided with a cross head located between said supportingmembers and attached to the other control rod, the said mechanisms bytheir location substantially symmetrically on opposite sides of the pumpserving to balance the entire structure, said cylinder being located ina closed hydraulic circuit comprising a fluid tank, a suction pipe lineextending from said tank and attachable to the inlet of the pump, apressure pipe line attachable to the outlet of the pump and to the ramand communicating with the cylinder on the larger area side of thepiston, a valved return line from the pressure pipe line tothe tank, athree way valve member, a casing for the valve member having three portscontrolled by the valve, said pressure pipe line being connected to oneof said ports, a pipe communi-' 6 eating with another of said ports andwith said tank, and a duct leading from the other port to the cylinderat the smaller area side of the piston. In testimony whereof, I havehereunto 1 subscribed my name. a

WALTER ERNST.

